In a production setting, it is usually not desirable to shut down
the cluster completely. In many cases, even when making
configuration changes, or performing upgrades to the cluster
hardware or software (or both), which require shutting down
individual host machines, it is possible to do so without shutting
down the cluster as a whole by performing a rolling
restart of the cluster. For more information about
doing this, see Section 7.5, “Performing a Rolling Restart of a MySQL Cluster”.